Eastern Bettong numbers booming inside fenced-off reserve in Canberra

There are plans to triple the size of a woodland sanctuary in Canberra's north, to make more room for growing numbers of a rare marsupial.

Eastern Bettongs from Tasmania were released into a fenced area at Mulligans Flat in mid-2012, as part of a program to boost their numbers.

Prior to their release, the last sighting of the small hopping animals on the Australian mainland was about 100 years before.

By the 1920s the native animals were wiped out by foxes, cats and habitat changes, except for some in Tasmania.

Researchers from the Woodlands and Wetlands Trust and Australian National University in Canberra have been celebrating the success of the latest breeding program.

The trust's Alison Russel-French said during the past 18 months, the introduced bettong population in the reserve had exploded from about 35 to 200.

"What we are looking to do is expand the current predator proof fence to triple its size which will probably pick up a lot of Mulligans and nearby Goorooyarroo [Nature Reserve].

"That would then allow these populations to expand even further."

Trust general manager Jason Cummings said the ACT Government had begun reserving more land, which would allow room for more bettongs and other species.

"In a bigger sanctuary we can have bigger animals, so we can possibly start to have some goannas or some quolls, and predatory animals that aren't in our landscape at the moment because they've been forced out by cats and foxes," he said.

Nearby suburbs are covered by cat containment legislation which means domestic cats must be kept indoors or in secure outdoor enclosures to prevent them hunting wildlife.

However the trust needs to raise $1.5 million to expand the predator proof fence around the proposed new breeding area.